The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Referring now to FIGS. 1 and 2, a non-powered photoluminescent paving brick 10 includes a paving brick base 14 that defines a cavity 16. A photoluminescent laminate structure 20 is attached in the cavity 16. The photoluminescent laminate structure is made before attachment in cavity 16. Glue, resin or other adhesive material and/or mechanical fasteners may be used to attach the photoluminescent laminate structure 20 in the cavity 16 of the paving brick base 14. For example, the photoluminescent paving brick 10 can be installed in a walkway to provide light during low light conditions. During daylight hours, the photoluminescent laminate structure 20 absorbs light energy. When the light is removed at dusk, the photoluminescent laminate structure 20 emits light or glows, which provides a non-powered source of light.
In FIG. 2, the photoluminescent laminate structure 20 may include first and second transparent layers 24 and 28 that sandwich an inner photoluminescent layer 26. The transparent layers 24 and 28 typically comprise glass or plastic. The inner layer 26 may comprise a resin layer with photoluminescent or phosphorescent particles suspended therein. The resin that is used typically cures in the absence of air since the resin layer is located between the transparent layers 24 and 28. The resin is typically solvent-based and experiences shrinkage as the solvent is released as a gas. The resin also typically has a relatively high viscosity and low compressive and tensile strength.
One problem associated with the approach shown in FIGS. 1 and 2 includes relatively high material cost for the glass or plastic layers 24 and 28. In addition, the manufacturing cost of the non-powered photoluminescent paving brick is also relatively high. In particular, creating a uniform layer of resin between the transparent layers 24 and 28 can be difficult.
In addition, the durability of the non-powered photoluminescent paving brick 10 may be suspect. There is a tendency for damage to occur when water seeps into gaps between the paving brick base 14 and the photoluminescent laminate structure 20. Since the paving brick 10 is typically installed outdoors, the paving brick 10 is subject to wide temperature variation and standing water. When the water freezes and thaws, it expands and contracts and the laminate structure 20 experiences relatively high pressure. In addition, the photoluminescent laminate structure 20 may experience delamination when soaked in water—even in the absence of freezing temperatures. As a result, the photoluminescent laminate structure 20 may tend to delaminate, break or separate from the paving brick base 14.
Furthermore, when an outer surface of the transparent layer 28 of the photoluminescent laminate structure 20 becomes wet, a coefficient of friction of the outer surface may be reduced. Since the paving brick 10 may often provide a walking surface, the non-powered photoluminescent paving brick 10 may be relatively slippery.